Search

Značajne količine raznovrsnih ostataka (odnosno lignocelulozne biomase) nastaju u poljoprivredi, prehrambenoj industriji i šumarstvu. Stoga je važno podići svijest o mogućnostima primjene takvih materijala koji se u današnje vrijeme ne bi trebali tretirati kao otpad, već se mogu koristiti kao obnovljive biotehnološke sirovine za proizvodnju kemikalija, drugih visokovrijednih proizvoda i biogoriva. Lignocelulozni materijal uglavnom sadrži celulozu, hemicelulozu i lignin. Predmet interesa ovog rada je lignocelulozni otpad iz poljoprivrede i prehrambene industrije kao mogući sirovinski temelj za napredak održive biotehnološke proizvodnje u Republici Hrvatskoj. Razmotrene su dostupne količine ovih lignoceluloznih sirovina, tipovi bioprocesa u kojima se one mogu koristiti, postupci predobrade koje je neophodno provesti prije provedbe samog bioprocesa te vrste biotehnoloških proizvoda koje je moguće dobiti., Significant amounts of various residues (i.e. lignocellulosic biomass) are generated in agriculture, food industry and forestry. Therefore, it is important to raise awareness about the possibilities of using such materials, which nowadays should not be treated as waste, but can be used as renewable biotechnological raw materials for the production of chemicals, other high-value products and biofuels. Lignocellulosic material consists mainly of cellulose, hemicellulose and lignin. The subject of interest of this paper is lignocellulosic waste from agriculture and the food industry as a possible raw material basis for the progress of sustainable biotechnological production in the Republic of Croatia. The available amounts of these lignocellulosic raw materials, the types of bioprocesses in which they can be used, the pretreatment procedures that need to be carried out before the implementation of the bioprocess itself, and the types of biotechnological products that can be obtained have been considered.

Istraživanja u okviru teze imaju za cilj dobijanje polimernih mreža kod kojih se regulacijom sirovinskog sastava i uslova sinteze mogu menjati svojstva siloksanskih materijala u skladu sa krajnjom primenom. Osnovni cilj istraživanja ove teze je razvoj novih postupaka sinteze hibridnih siloksanskih nanokompozita na osnovu različitih prekursora mreža. Takođe, ispitan je i uticaj različitih tipova funkcionalizacije površina nanopunila silicijum(IV) oksida (sa hidrofobnom i hidrofilnom površinom) na svojstva kompozitnih materijala za specifične namene. Nanokompoziti na osnovu polimernih mreža se uglavnom koriste u onim primenama gde tradicionalne polimerne mreže ne mogu da zadovolje potrebe koje se pred njih stavljaju. Zato je potrebno razviti postupak koji bi omogućio dobijanje materijala na osnovu polimernih mreža sa poboljšanim mehaničkim, elastičnim i toplotnim svojstvima. Motivacija je vođena potrebom razvoja novih kompozitnih materijala koji imaju jedinstvena mehanička, toplotna, termomehanička svojstva sa mogućnošću da pomognu u rešavanju problema okoline, kao što su problem sa prostorom, sa automobilima, u elektronici i infrastrukturi, i naravno, oni će biti veliki izazov u nauci materijala i industriji.Siloksanske mreže su dobijene od α, ω-divinil poli(dimetilsiloksana) i poli(metil-hidrogensiloksana) u odnosu 60/40; 50/50 i 40/60. Nanokompoziti su sintetisani dodavanjem različitih sadržaja nanopunila silicijum(IV) oksida (1, 2, 5, 10 i 20 mas.%). Za potvrdu pretpostavljenog mehanizma reakcije umrežavanja siloksana korišćena je FTIR spektroskopija. TEM analiza je korišćena za procenu topologije i potvrdila je dobru disperziju punila u polimernom matriksu. Dodavanje nanopunila poboljšava mehanička svojstva dobijenih materijala i povećanje vrednosti prekidne jačine za kompozite sa hidrofobnim silicijum(IV)oksidom je veće u poređenju sa kompozitima sa hidrofilnim punilima, što je očekivano zbog bolje kompatibilnosti hidrofobne matrice i hidrofobnih punila. Termogravimetrijska analiza korišćena je za analizu uticaja vrste funkcionalizacije silicijum(IV) oksida na termičku stabilnost siloksanskih elastomernihmaterijala. Kao što se i očekivalo, porast sadržaja nanopunila povećava termičku stabilnost dobijenih hibridnih materijala. Uticaj punila na temperature faznog prelaza siloksanskih materijala analiziran je diferencijalnom skenirajućom kalorimetrijom. Zbog slabije kompatibilnosti hidrofilnog punila i hidrofobne matrice primećeno je smanjenje vrednosti Tm, a najmanja vrednost temperature topljenja primećena je za uzorak sa najvećim udelom hidrofilnog punila.Uticaj nanopunila na mehaničke i termičke karakteristike dobijenih materijala biće detaljno analiziran, pri čemu je potvrđeno poboljšanje mehaničkih svojstava siloksanskih elastomera dodatkom nanopunila. U cilju razvoja novih biokompatibilnih materijala i poboljšanja svojstava biorazgradivosti siloksanskih materijala biće sintetisani ABA blok kopolimeri koji se sastoje od segmenata poli(dimetilsiloksana) i poli(laktida). Kao makroinicijator za sintezu blok kopolimera korišćen je polidimetilisiloksan, pa je polimerizacija laktida inicirana hidroksilnim grupama siloksana. Poli(laktid) se odlikuje veoma dobrim mehaničkim svojstvima i biorazgradivošću, dok se kopolimerizacijom sa siloksanima utiče na mehanička svojstva kao i na svojstva površine sintetisanog kopolimera., Research in the thesis aims to obtain polymeric networks in which the regulation of the rawmaterial composition and the conditions of the synthesis can alter the properties of the siliconematerials in accordance with the final application. The main goal of the research of this thesis isthe development of new procedures for the synthesis of hybrid silicone nanocomposites based ondifferent precursors. The influence of different types of surface functionalisation of nanofillers(with hydrophobic and hydrophilic functionalised surface) on the properties of compositematerials for specific purposes was investigated. Nanocomposites based on polymer networks aremainly used in those applications where traditional polymer networks cannot meet the needs thatare expected. It is therefore necessary to develop a process that would enable the production ofmaterials based on polymeric networks with improved mechanical, elastic and thermal properties.Motivation is driven by the need to develop new composite materials that have uniquemechanical, thermal, thermo-mechanical properties with the ability to help solve environmental problems, such as space problems, cars, electronics and infrastructure, and of course they will bea challenge in the material science and industry. Siloxane networks were prepared from α,ω-divinyl poly(dimethylsiloxane) and poli(methyl-hydrogen siloxane) with a ratio 60/40; 50/50 and40/60. Nanocomposites were synthesised with the addition of different contents of silicananofiller (1, 2 5, 10 and 20 wt%). For the confirmation of the presumed mechanism of siloxanecrosslinking reaction FTIR spectroscopy was used. TEM analysis was used for topologyevaluation and confirmed good dispersion of the fillers into the polymer matrix. Addition ofnanofillers increased the mechanical properties of obtained materials and greater increase of thetensile strength for the composites based on hydrophobic silicon(IV)-oxide was assessed,compared with the hydrophilic ones. It was expected due to better compatibility of hydrophobicsilicone matrix and hydrophobic filler particles. Thermogravimetric analysis was used for theevaluation of the influence of the types of silicon(IV)oxide functionalisation, on the thermaldegradation of elastomeric materials. As it was expected the increases of nanofillers contentincreased the thermal stability of obtained hybrid materials. The influence of fillers on the phasetransition temperatures of siloxanematerials was analysed with the differential scanningcalorimetry. Due to the lower compatibility of hydrophilic filler and hydrophobic matrixdecreasing of Tm values was observed, and the lowest value of melting temperature was noticedfor the sample with the highest loading of hydrophilic filler.In order to develop new biocompatible materials and improve the biodegradability properties ofsilicone materials, ABA types of block copolymers consisting of segments ofpoly(dimethylsiloxane) and poly(lactide) was synthesized. As a macroinitiator for the synthesis ofthe block copolymer, poly(dimethylisiloxane) was used, so the lactide polymerization starts fromthe hydroxyl groups of siloxanes. Poly(lactide) is characterized by poor mechanical propertiesand biodegradability, while copolymerization with silicones will affect the mechanical andsurface properties of the synthesized copolymer.

Proizvodnja biogoriva iz obnovljivih sirovina privukla je pažnju znanstvenika jer može poslužiti za opskrbu energijom i alternativnim gorivima. Bioetanol je jedno od najzanimljivijih biogoriva zbog njegovog pozitivnog utjecaja na okoliš. Najčešće se proizvodi iz sirovina koje sadržavaju šećer i škrob. Međutim, razni izvori lignocelulozne biomase, kao što su poljoprivredni i šumski ostaci te zeljasti energetski usjevi, također mogu poslužiti kao sirovine za proizvodnju bioetanola, energije, topline i kemikalija s dodanom vrijednošću. Lignoceluloza je složena mješavina ugljikohidrata, koju treba učinkovito prethodno obraditi da bi se oslobodili biotransformacijski putevi u kojima enzimi proizvode fermentabilne šećere što nakon hidrolize fermentiraju u etanol. Unatoč tehničkim i ekonomskim poteškoćama, obnovljive lignocelulozne sirovine imaju nisku cijenu te ne utječu na hranu i prehrambeni lanac, čime potiču održivost. Za proizvodnju bioetanola iz obnovljivih sirovina razvijeni su različiti načini rada bioprocesora. Osim toga, intenzivno se razvijaju i alternativni postupci odvajanja i pročišćavanja bioetanola. Ovaj rad daje pregled novih trendova u proizvodnji bioetanola iz različitih obnovljivih sirovina, te postupaka njegovog odvajanja i pročišćavanja., Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.

Cilj ovog diplomskog rada je istražiti primjenu viših alkohola (pentan-1-ola, oktan-1-ola, nonan-1-ola i oleil alkohola) kao ekstraktivnih otapala s visokim vrelištem za izdvajanje etanola iz fermentirane podloge u integriranom bioreaktorskom sustavu. Ekstrakcija etanola je istraživana u svrhu dobivanja ekološki, energetski i financijski učinkovitijeg procesa od uobičajeno primijenjene višestupanjske destilacije. Istraženo je toksično djelovanje ekstraktanta na kulturu kvasca Saccharomyces cerevisiae i ponašanje dvokomponentnih (ekstraktant–voda) odnosno trokomponentnih smjesa (ekstraktant-voda-etanol) te učinkovitost razdvajanja organske faze od podloge. Izrađeni su binodalni trokomponentni dijagrami za sustave pentan-1-ol/voda/etanol, oktan-1-ol/voda/etanol, nonan-1-ol/voda/etanol i oleil alkohol/voda/etanol. Na temelju binodalnih dijagrama izvršen je proračun potrebnih količina otapala za trostupanjski ekstrakcijski sustav i predložen je sustav tehnološke linije za izdvajanje etanola iz fermentirane podloge. The aim of this work was to investigate the application of higher alcohols characterized by high boiling points (i.e. pentan-1-ol, octan-1-ol, nonan-1-ol and oleyl alcohol) as extraction solvents for the ethanol extraction from broth, fermented in the integrated bioreactor system. The goal was the development of the ecologically, energetically and financially more efficient process than conventional multi-stage distillation. Applied extractants were tested for its toxicity on the Saccharomyces cerevisiae yeast culture. The behaviors of two-component systems (extractant-water) and three-component mixtures (extractant-water-ethanol) were investigated toward the efficiency of separation of organic phase (extract) and the water phase (rafinate). Binodal curves were constructed for systems: pentan-1-ol / water / ethanol, octan-1-ol / water / ethanol, nonan-1-ol / water / ethanol and oleyl alcohol / water / ethanol. Binodal diagrams were used for the calculations of required solvent amounts for the ethanol extraction in the three-stage extraction system. The plants for ethanol production based on extractions with higher alcohols were proposed.